The National Disaster Medical System (NDMS) Pilot Program was authorized by Congress to improve the interoperability, capabilities, and capacity of the NDMS. To develop a roadmap for planning and research, the mixed methods Military–Civilian NDMS Interoperability Study (MCNIS) was conducted in 2020-2021. The initial qualitative phase of the study identified critical themes for improvement: (1) coordination, collaboration, and communication; (2) funding and incentives to increase private sector preparedness; (3) staffing capacity and competencies; (4) clinical and support surge capacity; (5) training, education, and exercises between federal and private sector partners; and (6) metrics, benchmarks, and modeling to track NDMS performance. These qualitative findings were subsequently refined, validated, and prioritized through a quantitative survey. Expert respondents ranked 64 statements based on weaknesses and opportunities identified during the qualitative phase. Data were collected using Likert scales, and multivariate proportions and confidence intervals were estimated to compare and prioritize each statement's level of support. Pairwise tests were conducted for each item-to-item pair to determine statistically significant differences. The survey results corroborated the earlier qualitative findings, with all weaknesses and opportunities ranked as important by a majority of respondents. Survey results also pointed to specific priorities for interventions within the 6 previously identified themes. As with the qualitative study, the survey found that the most common weaknesses and opportunities were related to coordination, collaboration, and communication, especially regarding information technology and planning at the federal and regional levels. These priority interventions are now being developed, implemented, and validated at 5 pilot partner sites.